In general, an industrial robot refers to a general-purpose machine which has both motor functions and intelligence like human beings. Specifically, the industrial robot indicates a general-purpose machine which may be provided with an operating arm based on an engineering method, vision and tactile sensations to understand its environment, a function of planning and executing a working order by itself, and a unit to communicate with an operator, may freely operate, and may be programmed to perform various operations as an integrated mechanical system.
The industrial robot is designed to have an operation and loading weight optimized in the corresponding industrial field or operation process. Therefore, the industrial robot has a limitation in exhibiting different loading weights in various environments or processes like a common robot.
The common robot may refer to a robot which commonly uses a robot body. Specifically, only an end effector or tool in the robot body may be replaced depending on different operations, and a process program for a corresponding operation in a robot controller may be replaced to support another operation.
As shown in FIG. 1, a conventional polar coordinate robot includes joints 41, 42, 43 corresponding to two rotating axes 30 and 31 and one straight axis 20, and frames 51, 52, 53, which are formed over a base 10.
In the robot, a first joint 41 corresponding to the rotating axis 30 serves to rotate a first frame 51 about the base 10, a second joint 42 corresponding to the rotating axis 31 serves to vertically rotate a second frame 52 about the first frame 51, and a third joint 43 corresponding to the straight axis 20 serves to advance and retreat a third frame 53 with respect to the second frame 52.
Since the polar coordinate robot has an excellent vertical motion characteristic with respect to a vertical surface, the polar coordinate robot may perform an operation in a place of which the working area is wide and which is inclined. Therefore, the polar coordinate robot is suitable for a welding operation or coating process.
Meanwhile, when the conventional industrial robot inclusive of the polar coordinate robot is designed, it is very important to decide the loading weight of the industrial robot, in order to determine the use or purpose of the robot. The loading weight is decided by an actuator, a decelerator, a power transmission mechanism which form a joint.
Therefore, when the manufactured industrial robot is to be used for different use, there are difficulties in applying the industrial robot, as long as the loading weight thereof is not allowed. Therefore, a method capable of increasing the loading weight is strongly required.
In order to increase the loading weight, the actuator and the decelerator of the joint may be simply changed. In this case, however, the design of the robot is inevitably changed, an additional cost for purchasing a large actuator is required, and the weight of the robot body is increased. Therefore, this is almost the same as an operation of manufacturing a new industrial robot. An example for the structure for increasing the loading weight is disclosed in Korean Patent No. 10-519608 registered on Oct. 6, 2005.
Furthermore, since the conventional industrial robot may have a loading weight only within a predesigned and predetermined range, the conventional industrial robot cannot be used as a robot body of a common robot requiring different loading weights.
Furthermore, when the conventional industrial robot is docked with a separate robot for carrying the industrial robot or transferring the industrial robot, the weight of the robot body is limited. Accordingly, there are difficulties in unconditionally mounting the actuator and the decelerator having a large volume and weight on the robot.